EVALUATION OF MAXIM^® (3,5,6-TPA) FOR INCREASE IN YIELD, FRUIT SIZE AND RETENTION IN LITCHI, CV. HLH MAURITIUS, IN SOUTH AFRICA

Fruit size plays an important role as a quality parameter and is as important as yield in the determination of profitability in litchi production. There is a limited increase in fruit size through optimization of standard cultural practices like fertilization, irrigation and pruning. Auxins play an important role in fruit size as they stimulate cell division and enhance cell enlargement. Therefore, the application of auxins increases fruit growth rate and influences size, ripening time, colour and storage quality. Many attempts have been made to increase litchi fruit size. Maxim^® (3, 5, 6-TPA), a synthetic auxin, has shown good results on litchis in many countries including Israel, China and South Africa. Maxim^® is already registered for citrus in South Africa and registration on litchis is planned. The aim of this research, therefore, was to evaluate Maxim^® for the increase in fruit size and fruit retention in litchi (Litchi chinensis Sonn.), cv. HLH Mauritius, for the registration of Maxim^® in South Africa. In the first year (2005/06) Maxim^® was applied at the 1-, 2- and 3-g fruit let stage at 20 and 40 ppm, and the effect on yield and fruit size was determined. All treatments increased yield and fruit size, with the 40 ppm treatment at the 3-g stage performing best. In the second year (2006/07) the Maxim^® applications were extended due to the first year’s results. Maxim^® was applied at the 2-, 3- and 4-g fruitlet stage at 20, 40 and 80 ppm. The effect on yield, fruit drop and fruit size was determined. All treatments increased yield and fruit size. The applications at the 3- and 4-g fruitlet stage, after the second natural fruit drop, proved to be most beneficial in increasing litchi fruit size. Considering the data obtained in both years, Maxim^® application at 40 ppm after the second natural fruit drop (3- to 4-g stage) can be recommended. Furthermore, economic calculations revealed that the application of Maxim^® can benefit producers financially.